Can't texture paint properly
It is difficult to tell without the actual Blender file, but in the image provided, some of your UV islands are in fact overlapping and others are quite close together.



To fix this, select all of the faces in edit mode and then, with your cursor over the UV window, hit Ctrl + P. This will automatically arrange the UV islands. In the 3D viewport window, in the tools panel (far left of the image), you can then set a margin, which you'll want to avoid this bleeding.



Additionally, you can set the bleed amount option in Texture Paint Mode to 0px, but this may cause problems later on. Especially if you want to use a subdivision surface modifier on the model.